AB1002 LONGER DIAGNOSTIC DELAY, SEVERE FATIGUE AND LESS USE OF TNF-INHIBITORS ARE ASSOCIATED WITH UNACCEPTABLE AXIAL PAIN IN 354 SWEDISH PATIENTS WITH ANKYLOSING SPONDYLITIS
Authors: A. Deminger, Å. Wilde, E. Klingberg, J. Backman Renman, H. Forsblad-D’elia
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Pain has been shown to be the most important consequence of the disease in affecting health in patients with axial spondyloarthritis<sup>[1]</sup>. <h3>Objectives</h3> To assess factors associated with unacceptable axial pain in patients with long-standing ankylosing spondylitis (AS) overall and by sex. <h3>Methods</h3> Patients with AS (modified NY-criteria) from two geographically separated regions in Sweden were included in this cross-sectional, observational study. Primary outcome was axial pain (question number 2 from Bath Ankylosing Spondylitis Disease Activity Index (BASDAI)) dichotomised in VAS &lt; or ≥ 4 based on patient unacceptable pain<sup>[2]</sup>. Independent variables were selected based on previous knowledge and hypotheses of factors associated with pain. Information was collected from questionnaires (demographics, lifestyle habits, fatigue (BASDAI question number 1), symptoms of depression (from EQ-5D), medications), calculation of body mass index (BMI), blood sample (C-reactive protein (CRP)), and lateral spinal radiographs (assessment of spinal new bone formation with modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS)). Univariate and multivariable logistic regression analyses (dependent variable VAS axial pain ≥ 4) were used overall and stratified by sex. Variables with univariate <i>p</i>-values ≤ 0.1 were included in the multivariable model if not too highly correlated. <h3>Results</h3> In total, 354 patients were included, 62 % men, mean (SD) age 52 (13) years, symptom duration 27 (13) years and delay in diagnosis 9 (8) years. Mean (SD) VAS axial pain was 4.2 (2.6) with no significant difference between men and women (p = 0.30). However, in patients with unacceptable axial pain (VAS ≥ 4), n=177 (50%), significantly higher proportion of women reported unacceptable pain compared to men, 57 % vs 46 %, p = 0.049. In univariate analyses, unacceptable axial pain was associated with longer disease duration, longer delay in diagnosis, more severe fatigue, more symptoms of depression, lower alcohol consumption and less treatment with TNF-inhibitors. There was no association between unacceptable axial pain and age, civil state single, educational level, BMI, smoking status, mSASSS, CRP or use of NSAIDs. In the multivariable analysis, unacceptable axial pain was independently associated with longer delay in diagnosis and more severe fatigue, whereas use of TNF-inhibitor reduced the risk of having unacceptable pain (Figure 1). In the multivariable analyses stratified by sex, the same variables were associated with unacceptable pain in men as in the whole group; OR (95 % CI) for delay in diagnosis 1.08 (1.03 to 1.14), fatigue 2.0 (1.65 to 2.41) and use of TNF-inhibitor 0.23 (0.09 to 0.61). In women, fatigue was the only factor independently associated with unacceptable axial pain, OR (95 % CI) 1.32 (1.12 to 1.56). <h3>Conclusion</h3> In this cross-sectional study of patients with long-standing AS, 50 % of the patients had unacceptable axial pain. Even though a higher proportion of the women were affected, female sex was not independently associated with unacceptable axial pain. There were some sex-differences. Delay in diagnosis was associated with higher risk, and use of TNF-inhibitor was associated with lower risk of unacceptable axial pain only in men. The sex-difference possibly due to few women using TNF-inhibitors. Fatigue was independently associated with axial pain in both sexes. This study underpins the importance of early diagnosis in AS. <h3>References</h3> [1]U. Kiltz et al. <i>Rheumatology</i> 2016, 55 (10):1771–1776 [2]F. Tubach et al. <i>Arthritis Care &amp; Research</i> 2012, 64 (11):1699-1707 <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.